Abstract

Background:Induction of labor is an increasingly being done obstetric procedure throughout the world. It is carried out in approximately 20% of all pregnancies. It is associated with poorer outcomes when compared with spontaneous labor. Method: Institutional based cross sectional study was made on medical records of 294 women admitted for induction of labor in Hawassa public health facilities from 1st Jan, to 31st Dec, 2014. Systematic sampling technique was used to select samples. Data was collected by structured questionnaire and edited, then entered into Epi-Data version 3.1. Data was analyzed with Statistical Package for Social Science, version 21. First percentage, frequency and mean were calculated. Then, multivariable logistic regression analysis was done to evaluate the possible association of all variables that were candidate after binary logistic regression analysis. P-value of less than 0.05 in multivariable logistic regression was considered as statistically significant. Finally the result is summarized and presented in texts and charts. Result: The prevalence of failed induction of labor was 17.3%. Multivariable logistic regression analysis showed that advanced maternal age [AOR 9.21 (2.70-31.35)], Nulliparity [AOR 3.11 (1.01-9.62)], poor Bishop Score [AOR 4.54 (1.56-13.19)], greater for gestation [AOR 6.57 (2.18-19.72)], bad obstetric history [AOR 5.60 (1.35-23.29)], post term [AOR=4.52 (1.20-17.00)] and premature rapture of membrane [AOR 5.66 (1.96-16.32)] were significantly associated with failed induction of labor. Conclusion: Advanced age, Primiparity, unfavorable bishop score, premature rupture of membrane, greater for gestation and bad obstetric history had positive association with failed induction of labor. Developing practice guidelines may help to prevent unwarranted case selection and help to reduce the current high failure rates.

Introduction

Labor is the physiological process by which regular painful uterine
contractions result in progressive effacement, dilatation of the cervix and ultimately leads to delivery of the fetus through the birth canal [1].
Induction of labour is defined as an intervention designed to artificially
initiate uterine contractions leading to progressive dilatation and
effacement of the cervix and birth of the baby [2].

The risks associated with induction of labor include uterine hyper
stimulation, increased rates of operative deliveries and caesarean
sections (in those that undergo induction), fetal heart rate pattern
abnormalities, premature deliveries, infections in some cases and in the
worst scenario may result in a uterine rupture [3].

Induction of labor is carried out in approximately 20% of
pregnancies. It has been strongly associated with poor maternal
and perinatal outcomes [4]. In developed countries, up to 25% of
all deliveries at term now involve induction of labour. In developing countries, the rates are generally lower, but in some settings they can be
as high as those observed in developed countries [3].

The study done in a health resource poor setting showed induction
of labor giving an induction rate of 11.5 %, [5]. It is lower in African
region as shown by the recent WHO Global Survey dealing with
determinants of use of induction of labor in Africa showing an average
rate of induction ranging from 1.4% to 6.8% [6].

In Ethiopia, including the study area, induction of labor is a
commonly performed procedure but there is a limitation in undertaking
a study on the magnitude and factors associated with its failure. The latest
EDHS report that was done in the year 2011 didn’t include information
on induction of labor [7]. The consequence of a failed induction that
usually result in a Cesarean-section, compared to vaginal birth, is more
potential health risks to the woman and the baby, as well as, a significantly
longer recovery period for the woman. Therefore, an induction of labor
should be recommended only when it is necessary [8].

This study aimed at determining the prevalence of failed induction of labor and identifying associated factors in Hawassa public Hospitals
of Ethiopia.

In Ethiopia, including the study area, induction of labor is
a commonly performed procedure but there is a limitation in
undertaking a study on the magnitude and factors associated with its
failure. The latest EDHS report that was done in the year 2011 didn’t
include information on induction of labor [7]. The consequence of a failed induction that usually result in a Cesarean-section, compared
to vaginal birth, is more potential health risks to the woman and the
baby, as well as, a significantly longer recovery period for the woman.
Therefore, an induction of labor should be recommended only when it
is necessary [8].

This study aimed at determining the prevalence of failed induction
of labor and identifying associated factors in Hawassa public Hospitals
of Ethiopia (Figures 1 and 2).

Materials and Methods

A facility based cross sectional study was conducted at the public
health facilities of Hawassa town, southern Ethiopia from Mar
15th to April 15th, 2015. There are one referral hospital, one district
hospital and nine health centers in the City administration. The single
population formula was used to calculate a sample size, by using 50%
of the proportion of failed induction of labor. The sample size was
allocated for each health facility proportionally. Systematic random
sampling technique was used to select the samples from the list of
women with induction of labor.

Data was collected from medical records of women for whom
induction of labor was performed in Hawassa public health facilities using
pre tested structured checklist. Items were developed for this study to assess
socio demography factors, obstetric factors, types of induction performed
and health indication for labor induction. Checklist consist five sections
that have a total of 21 items which describe the purpose of the study.

Each completed checklist was coded on pre-arranged coding
sheet by principal investigator and edited to minimize errors. Then
data was entered in to Epidata version 3.1 to control data entry errors
and exported to SPSS version 21 for analysis. Percentage, frequency
and mean were calculated. Bivariate analysis was performed between
dependent variable and each of the independent variables, one at a
time. Their Odds ratio (OR), at 95% CI and p-value was obtained. All
variables found to be significant at bivariate level (at p-value <0.25%)
has been entered in to multivariable analysis using the binary logistic
regressions model to test the significance of its association.

Ethical clearance letter was obtained from ethical review board of
Jimma University College of health sciences. Official permission letters
was also obtained from Hawassa city health department and all the
respective study health facilities. Confidentiality and anonymity of the
record had been ensured throughout the execution of the study by taking
only the required information without using the name of the client.

Results

Socio-demographic factors

A total of 294 medical records of mothers who gave birth after
induction of labor were selected for study purpose. The mean age and
standard deviation of the selected women was 26.29 4.133 and 242 of all
samples were below 30 years of age (Figure 3).

Figure 3: The age category among mothers for whom induction of labor has
been done in Hawassa public health facilities, Ethiopia, 2014.

Obstetric factors

The mean fetal gestational age with its standard deviation was 38.95
and 2.57 respectively. The result showed that 55.8% of the women in the
study were primigravidas. The Bishop score of 185 study participants
was less than five before induction of labor (Figure 4).

Figure 4: Pre-induction Bishop Score of the mothers for whom induction of
labor has been done in Hawassa public health facilities, Ethiopia, 2014.

Indications for labor induction

The result showed that the predominant indications for induction
of labor in the study area were premature rapture of membrane,
Preeclampsia, Post term and Chorioamnionitis (Table 1).

Methods of Induction

The most commonly used methods of induction of labor in the
study were oxytocin infusion (73.5%) and oral or vaginal misoprostol
(26.5%).

Maternal prenatal and antenatal factors

There was a previous history of abortion in 9.5% of the study
participants, while there were other previous obstetric complication
experiences in 5.4% of them. The length of time for induction of
labor varied from 2 to 23 hr with its mean and standard deviation to
be 8.89 and 4.08 respectively. The tone of pregnancy in all mothers
was singleton. Out of the total samples, 181(61.6%) mothers ended
with vaginal delivery while others delivered by cesarean section
(Figure 5).

Figure 5: Mode of delivery among women delivered after induction of labor in
Hawassa Public health facilities, Ethiopia, 2014.

The Apgar scores of the newborns at first minute in 70.1% of the
cases were greater than seven, but at fifth minute the score of 83.3% of
newborns became greater than seven.

Figure 6: Frequency of reasons for cesarean section among women delivered
after induction of labor in Hawassa Public health facilities, Ethiopia, 2014.

Factors associated with failed induction of labor

Different variables that were assumed to be associated with
failed induction of labor were assessed first by using bivariate then
multivariable logistic regression analysis methods. There were eleven
variables showing significant association with the outcome variable
when entered into bivariate logistic regression model analysis. These
were: parity, pre-labor rapture of membrane, and age of the mother, preinduction
bishop score (a tabulated clinical score used to determine how
successful an induction of labour will be based on five characteristics
of the cervix: dilatation, length, consistency, station and position.
A Bishop’s score of 7 and above is said to be favorable for induction
of labor, see Table 1, premature rapture of membrane, mothers with
age greater than 30 years, and preterm rapture of membrane, post
term, previous obstetric complications, fetal gestation and length of
induction.

Cervix

Score

0

1

2

3

Dilatation(cm)

<1

2-Jan

4-Mar

>4

Length of cervix (cm)

>3

2

1

<1

Station

-3

-2

-1, 0

+1, +2

Consistency

Firm

Medium

Soft

----

Position

Posterior

Midpoint

Anterior

----

Table 1: Modified Bishop scoring.

However; multivariable logistic regression analysis showed that the
odds of failed induction were 3.11 times more likely in Primiparous
mothers [AOR=3.118 (1.01-9.62)] than multiparous one; the odds
of failed induction were 9.21 times more likely in mothers with age
greater than 30 years [AOR=9.210 (2.70-31.35)] than others; the odds
of failed induction were 4.54 times more likely in mothers with pre-induction bishop score of less than five [AOR=4.543 (1.56-13.19)] than
those with pre-induction bishop score of greater than five; the odds of
failed induction were 5.66 times more likely in mothers with premature
rapture of membrane [AOR=5.661 (1.96,16.32)] than others; the odds
of failed induction were 6.57 times more likely in mothers with greater
for gestation [AOR=6.571 (2.18,19.72)] than others, the odds of failed
induction were 4.52 times more likely in mothers with post term
[AOR=4.523 (1.20,17.00)] than others; the odds of failed induction were
5.60 times more likely in mothers with previous obstetric complications
were to have failed induction [AOR=5.609 (1.35,23.29)] than those
with no bad obstetric history (Table 2).

Discussion

Induction of labor is one of the fastest growing procedures in
current obstetric practice. American studies have documented a
nationwide more than doubling of induction rates between the late
eighties and the late nineties [9]. The recent rapid increase in induction
of labor particularly for debatable indications has generated concern
among clinicians.

This study showed that the prevalence of failed induction of labor
was 17.3%, which is greater than the study done in Health Resource
Poor Settings [5]. This difference may be due variation in commonly
used methods for induction of labor, in which oxytocin infusion was
the predominantly used method in the study area while in the other
cases misoprostol with other alternatives like Balloon catheter was used
as a common practice. The difference may also be due to unavailability
of adequate facilities in the study facilities as there are complicated
obstetric cases being handled.

The common indications for induction of labor in the study area
were premature rapture of membrane, Preeclampsia. Greater gestation,
however, the study done in Kathmandu Medical College Teaching
Hospital showed predominant indications for induction were: post term
pregnancy, PROM, oligohydramnious, and others [10]. In the study
done at a regional hospital in KwaZulu-Natal, South Africa the three
main indications for induction of labor were hypertensive disorders,
post-dates pregnancy and pre-labour rupture of the membranes [11].

The finding of this study also showed that the odds of failed
induction were 3.11 times more likely in primiparous mothers. This
finding, though it was higher, is supported by the study done by
Ramayahji RT, et al. in Kathmandu Medical College Teaching Hospital
[10] and the finding of N. Khan, et al. at Aga Khan University Hospital
[12].

The higher failure rate in the present study may be due to the higher
proportion of primiparous women in the study; it may also be for the reason that lack of important practices like use of cervical primers prior
to induction and delayed amniotomy in the active stage of labour.

In this study, mothers with age greater than 30 years were found
to be more at risk (28.8%) than others (6.4%) to have failed induction
of labor, which is supported by the study done in Kathmandu Medical
College Teaching Hospital [10].

The odds of failed induction were 4.54 times more likely in women
with Bishop Score of 5 or less. The study done by Maria Olender, et al.
also showed that Bishop score was inversely correlated with induction
failure showing a predictable deline in success with lower scores [13].
The finding of this study shows that inducing of labor should better be
performed at favorable cervix for a good outcome. It also supports the
scientific findings of different literatures that the condition of the cervix
at the start of induction is an important predictor, with the modified
Bishop score being a widely used scoring system. Induction of labor
results in high failure rate if the cervix is not ripe [14,15].

The odds of failed induction were 6.57 times more likely in women
with greater for gestation than others. This finding is in line with the
study done in Aga Khan university Hospital [12]. This may be related
with inaccurate determination of gestational age to ascertain greater for
gestation that may sometimes be an obstetric dilemma due to unsure
date of the last menstrual period and non-availability of early dating
ultrasound scan as often the case in resource constrained settings. It
might also be due to the practice of early induction at 40 weeks by the
obstetricians which may be because of lack of facilities for intensive care.

This study also showed that mothers with bad obstetric history
were 5.60 times more likely to have failed induction than others. This
is supported by the study finding of Neelofur Babar Khan, et al. at Aga
Khan University Hospital [10]. This may be for the reason that women
with previous obstetric complications many times are not allowed to go
beyond 40 weeks and therefore will have unfavorable cervix conditions
at time of induction.

The mostly used method of induction in the study area was oxytocin
infusion (72.8%), this is in contrary with the study done in regional
hospital of KwaZulu-Natal, South Africa where the most commonly used
methods of IOL were oral misoprostol (63.5%) and vaginal misoprostol
(30.3%) [11] and the finding of the study done in health resource poor
setting in Catholic Maternity Hospital in Ogoja , Nigeria indicated that
use of misoprostol took the higher score78.2% [5]. The reason for use
of oxytocin as the most common method of induction of labor in the
study area may be its better availability in the study settings or it may be
due to the induction protocol of the facilities.The proportion of failure
of induction of labor when using oxytocin infusion was higher (19.4%)
as compared to that of using misoprostol (11.5%). This is supported by
the study conducted by Bangal BV, et al. and Ezechu AC, et al. [16,17].
The study finding also showed that relatively safe methods of induction
of labor such as the Foley catheter were not used at the study site. This
may be due to the induction protocol of the study facilities probably
reinforced the use of oxytocin infusion and misoprostol as the main
modes for induction of labor [18-20]. (Table 3).

Conclusion

The prevalence of failed induction of labor was relatively high in the
study area. Variables which increased the likelihood of failed induction
were advanced maternal age, unfavorable bishop score, postdates
delivery, premature rupture of membrane, mothers with age greater
than 30 years and previous obstetric complications.

Competing interests

The authors declare that they have no competing interests.

Author’s contributions

All authors participated in the design and analysis of the study.MG searched
the databases, and wrote the first and second draft of the article. TB and BF
reviewed proposal development activities and each drafts of the result article. All
authors revised the manuscript and approved the final version.

Acknowledgements

First and foremost we would like to greatly thank the almighty God, the
foundation of knowledge and wisdom for enabling me to achieve this task. We
also would like to thank Jimma University College of health science for providing
us with the fund to conduct this thesis. We extend our thanks to Jimma University
ICT Department that provided us with the access for internet service. Lastly, but
not least, we offer our regards to all who helped us throughout this thesis work
including health care managers and service providers of study area.